Sputtering Equipment

Abstract

To improve furthermore uniformity of film deposition.SOLUTION: A sputtering device (100) includes multiple antennas (5) arrayed along the surface of a substrate (W) held by a substrate holding part (3) in a vacuum vessel (2), for generating plasma, and expansion plates (20a-20b) for expanding a surface on the deposition side of the substrate (W) is disposed so as to have a contact with or become close to each of ends (W1-W2) of the substrate (W) held by the substrate holding part (3).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sputtering apparatus that sputters a target using plasma to form a film on a substrate. [Background technology]

[0002] In addition to magnetron sputtering devices, there are also sputtering devices described in Patent Documents 1 and 2, for example, in which an antenna is placed near a target and a high-frequency current is passed through the antenna to generate plasma for sputtering. In these sputtering devices, the plasma density is smaller than in so-called magnetron sputtering devices, which generate plasma using a magnet. The smaller plasma density is expected to improve the target utilization efficiency and the uniformity of film formation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-154875 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-37555 Summary of the Invention [Problem to be solved by the invention]

[0004] While the sputtering apparatuses disclosed in Patent Documents 1 and 2 can improve the uniformity of film formation to some extent, they are still not sufficient. For example, in Patent Document 1, the volume of the discharge space varies depending on the position of the substrate to be sputtered, and the plasma density distribution also varies, resulting in variations in film formation depending on the position of the substrate. In particular, the discharge volume is larger near the edges of the substrate than at the center, resulting in lower plasma density and reduced film thickness. In addition, in Patent Document 2, the deposition shield to prevent film deposition behind the substrate is located closer to the target than the substrate, resulting in more shielding of sputtered particles than necessary. In particular, the deposition shield is positioned so that it slightly overlaps the edge of the substrate to prevent film deposition behind the substrate, resulting in reduced film thickness at the edge of the substrate.

[0005] An object of one embodiment of the present invention is to further improve the uniformity of film formation in a sputtering apparatus using plasma generated by an antenna. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention provides a sputtering apparatus that uses plasma to sputter a target to form a film on a substrate, and is equipped with a vacuum vessel that is evacuated and into which gas is introduced, a substrate holding section that holds the substrate within the vacuum vessel, and an extension member that extends the surface of the substrate on the film-forming side, and is characterized in that the extension member is arranged on the substrate holding section so as to contact or be in close proximity to an edge of the substrate when the substrate is held by the substrate holding section. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to improve the uniformity of film formation on a substrate. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a vertical cross-sectional view perpendicular to the longitudinal direction of an antenna, schematically illustrating the configuration of a sputtering apparatus according to a first embodiment of the present invention. [Figure 2] 2 is a perspective view showing a state in which a substrate on which a film is formed by the sputtering apparatus shown in FIG. 1 is held by a substrate holding member. FIG. [Figure 3] 2 is a schematic diagram showing the positional relationship between the antenna, the target, and the substrate in the embodiment. FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along the line AA′ in FIG. 3. [Figure 5] FIG. 4 is a schematic diagram showing the diffusion distribution of sputtered particles in the embodiment. [Figure 6] 2 is a vertical cross-sectional view perpendicular to the longitudinal direction of the antenna, schematically showing the density of sputtered particles in a vacuum chamber during film formation in the sputtering apparatus shown in FIG. 1. FIG. [Figure 7] 2 is a vertical cross-sectional view perpendicular to the longitudinal direction of the antenna, schematically illustrating the density of sputtered particles in a vacuum chamber during film formation when an extension plate is not provided on a substrate in the sputtering apparatus shown in FIG. 1. FIG. [Figure 8] 2 is a vertical cross-sectional view perpendicular to the longitudinal direction of the antenna, schematically showing the density of sputtered particles in a vacuum chamber during film formation in the sputtering apparatus shown in FIG. 1, with the substrate being transported in the scanning direction. [Figure 9] FIG. 2 is a longitudinal cross-sectional view perpendicular to the longitudinal direction of the antenna, which schematically shows the density of sputtered particles in a vacuum chamber during film formation when an extension plate is not placed on the substrate and the substrate is transported in the scanning direction in the sputtering apparatus shown in FIG. [Figure 10] 10 is a graph showing the film thickness distribution with and without an extension plate. [Figure 11] 10 is a graph showing the film thickness distribution depending on the width of the extension plate. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Embodiment 1] Hereinafter, one embodiment of the present invention will be described in detail.

[0010] (Sputtering equipment overview) 1 is a schematic cross-sectional view of a sputtering apparatus 100 according to this embodiment. The sputtering apparatus 100 sputters a target T using an inductively coupled plasma P to form a film on a substrate W. Here, the substrate W is, for example, a substrate for a flat panel display (FPD) such as a liquid crystal display or an organic EL display, a flexible substrate for a flexible display, or the like.

[0011] 1, the sputtering apparatus 100 includes a vacuum vessel 2, a substrate holder 3 that holds a substrate W, a target holder 4 that holds a target T, a plurality of linear antennas 5, and a high-frequency power supply 6 that applies high-frequency power to the plurality of antennas 5. As a result, when a high frequency is applied to the plurality of antennas 5 from the high-frequency power supply 6, a high-frequency current IR flows through the plurality of antennas 5, an inductive electric field is generated within the vacuum vessel 2, and an inductively coupled plasma P is generated.

[0012] The vacuum vessel 2 is, for example, a metal vessel, and its interior is evacuated to a vacuum by a vacuum exhaust device (not shown). The vacuum vessel 2 is electrically grounded. A sputtering gas or a reactive gas is introduced into the vacuum vessel 2. The sputtering gas and the reactive gas may be selected according to the processing to be performed on the substrate W. The sputtering gas is, for example, an inert gas such as argon (Ar). The reactive gas is, for example, oxygen (O2) or nitrogen (N2).

[0013] As shown in FIG. 2 , the substrate holding unit 3 is a holder that holds a flat substrate W. The substrate holding unit 3 also holds extension plates 20a and 20b. The extension plates 20a and 20b are extension members that extend the surface of the substrate W on the film formation side. The extension plates 20a and 20b are arranged on the substrate holding unit 3 so as to be in contact with or close to the ends W1 and W2 of the substrate W when the substrate W is held by the substrate holding unit 3. In this case, the extension plates 20a and 20b do not have to be arranged to be in contact with both the ends W1 and W2, but may be arranged close to both the ends W1 and W2. Furthermore, instead of being arranged close to both the ends W1 and W2, the extension plate 20a (20b) may be arranged to be in contact with one end W1 (W2) and the extension plate 20b (20a) close to the other end W2 (W1). The extension plates 20a and 20b are detachably fixed to the substrate holder 3 by screws or the like. Therefore, after each film formation is completed, the substrate W is removed from the substrate holder 3, but the extension plates 20a and 20b are left in place. The substrate holder 3 holds the substrate W together with the extension plates 20a and 20b in a horizontal position within the vacuum chamber 2, for example, and is configured to be scanned back and forth linearly within the vacuum chamber 2, as will be described later.

[0014] The extension plates 20a and 20b are arranged on both sides of the substrate W so that their surfaces (surfaces facing the target T) are flush with the surface of the substrate W (surfaces on the film formation side). In this embodiment, an example is described in which the extension plates 20a and 20b are arranged so as to contact the longitudinal ends W1 and W2 of the substrate W. However, they may be arranged so as to contact or be close to all ends of the substrate W, including the lateral ends. In this case, the extension plates may not only be in contact with all ends, but also be close to all ends. Furthermore, instead of being close to all ends, the extension plates may be arranged so as to contact some ends and be close to the remaining ends.

[0015] The target holder 4 holds the target T, facing the substrate W and extension plates 20a and 20b held by the substrate holder 3. The target T in this embodiment is a flat plate that is rectangular in plan view. The target holder 4 is provided on a side wall 2a (e.g., the upper wall) that forms the vacuum vessel 2. An insulating part 9 with a vacuum sealing function is provided between the target holder 4 and the side wall 2a of the vacuum vessel 2. A target bias power supply 10 that applies a target bias voltage to the target T is connected to the target T via the target holder 4. The target bias voltage is a voltage that attracts ions in the plasma P to the target T and causes sputtering.

[0016] In this embodiment, a plurality of target holders 4 are provided. The plurality of target holders 4 are arranged in parallel on the same plane on the front surface side of the substrate W in the vacuum chamber 2, along the front surface of the substrate W (for example, substantially parallel to the rear surface of the substrate W). The plurality of target holders 4 are arranged at equal intervals so that their longitudinal directions are parallel to one another. As a result, the plurality of targets T arranged in the vacuum chamber 2 are arranged at equal intervals so that they are substantially parallel to the front surface of the substrate W and so that their longitudinal directions are parallel to one another, as shown in FIGS. 1 and 4. Note that each target holder 4 has the same configuration.

[0017] The multiple antennas 5 are arranged in parallel on the same plane on the front surface side of the substrate W in the vacuum chamber 2, along the surface of the substrate W (for example, substantially parallel to the surface of the substrate W). The multiple antennas 5 are arranged at equal intervals so that their longitudinal directions are parallel to one another. As shown in Fig. 3, each antenna 5 has a linear shape and the same configuration in a plan view, and its length is several tens of centimeters or more.

[0018] As shown in FIGS. 1 and 3, the antennas 5 of this embodiment are arranged on both sides of the targets T held by each target holder 4. That is, the antennas 5 and the targets T are arranged alternately, with one target T sandwiched between two antennas 5. Here, the longitudinal direction of each antenna 5 is the same as the longitudinal direction of the targets T held by each target holder 4. Furthermore, as shown in FIG. 4 in particular, the targets T are arranged so that the pitch width of the multiple targets T and the pitch width of the multiple antennas 5 are the same (both are pitch width Y). Furthermore, the antenna 5 arranged between two targets T is arranged at a position equidistant from the two targets T.

[0019] The material of each antenna 5 is, for example, but not limited to, copper, aluminum, an alloy thereof, stainless steel, etc. The antenna 5 may be hollow and a refrigerant such as cooling water may be passed through it to cool the antenna 5.

[0020] Furthermore, the portion of each antenna 5 located inside the vacuum vessel 2 is covered with a straight tubular insulating cover 12 made of an insulating material. There is no need to seal between both ends of this insulating cover 12 and the vacuum vessel 2. This is because even if gas enters the space inside the insulating cover 12, the space is small and the electrons have a short travel distance, so plasma P is not normally generated in the space. The material of the insulating cover 12 is, for example, quartz, alumina, fluororesin, silicon nitride, silicon carbide, silicon, etc., but is not limited to these.

[0021] A high frequency power supply 6 is connected to the antennas 5. The antennas 5 may be provided with an impedance adjustment circuit such as a variable capacitor or a variable reactor to adjust the impedance of each antenna 5. By adjusting the impedance of each antenna 5 in this manner, the density distribution of the plasma P in the longitudinal direction of the antenna 5 can be made uniform, and the film thickness in the longitudinal direction of the antenna 5 can be made uniform.

[0022] With the above configuration, a high frequency current IR can be applied from the high frequency power supply 6 to the antenna 5. The frequency of the high frequency is, for example, a common 13.56 MHz, but is not limited to this.

[0023] The sputtering apparatus 100 of this embodiment has a reciprocating scanning mechanism 15 that reciprocally scans the substrate holding unit 3. The reciprocating scanning mechanism 15 causes the substrate holding unit 3 to reciprocate along the arrangement direction X of the antennas 5, thereby causing the substrate W and extension plates 20a and 20b held by the substrate holding unit 3 to reciprocate along the arrangement direction X of the antennas 5.

[0024] The reciprocating scanning mechanism 15 mechanically reciprocates the substrate holder 3 along the arrangement direction X of the antennas 5, thereby causing the substrate W and extension plates 20a and 20b held by the substrate holder 3 to reciprocate on the same plane along the arrangement direction X. The forward and backward movements of the substrate W by this reciprocating scanning mechanism 15 are linear movements, and the forward and backward movements are configured to overlap each other. The reciprocating scanning mechanism 15 may include, for example, an actuator provided outside the vacuum chamber 2 and a linear guide connected to the substrate holder 3 and driven by the actuator.

[0025] 3 and 4, the reciprocating scanning mechanism 15 is configured so that the scanning range SR of the substrate W and the extension plates 20a and 20b is equal to the pitch width Y. Specifically, the scanning range SR of the substrate W is configured to be equal to the pitch width Y by a control device (not shown) that controls the reciprocating scanning mechanism 15. In other words, the substrate W and the extension plates 20a and 20b are scanned reciprocally with an amplitude of ±Y / 2, with the initial position as the center position O.

[0026] In a configuration in which multiple targets T and multiple antennas 5 are alternately arranged, as in this embodiment, the diffusion ranges of sputtered particles emitted from each target T overlap, as shown in FIG. 5. On the other hand, if the substrate W and extension plates 20a and 20b are not scanned, a distribution of film thickness and film quality with a period a may occur on the substrate surface. Here, the scanning range SR of the substrate W by the reciprocating scanning mechanism 15 has the same pitch width Y as the pitch width Y of the targets T, so that the distribution of film thickness and film quality with a period a that may occur on the substrate surface can be leveled, thereby improving the uniformity of the film formation. Incidentally, providing extension plates 20a and 20b on the substrate W can further improve the uniformity of the film formation. This point will be explained below.

[0027] (Improved uniformity of film formation) As shown in FIG. 6, when extension plates 20a and 20b are provided at the respective ends (W1 and W2) of the substrate W and positioned approximately in the center of the vacuum chamber 2, the extension plates 20a and 20b suppress the spread of plasma P. As a result, the density of sputtered particles (indicated by the thick arrows in the figure) on the surfaces of the substrate W and the extension plates 20a and 20b is approximately the same. In this case, the provision of extension plates 20a and 20b at the respective ends (W1 and W2) of the substrate W prevents the plasma P from spreading at the ends of the substrate W, and therefore the density of sputtered particles at the ends (W1 and W2) of the substrate W does not decrease. This prevents the thickness of the film formed from the center of the substrate W toward the ends (W1 and W2) from decreasing, resulting in improved film uniformity.

[0028] On the other hand, when the extension plates 20a and 20b are not provided and the substrate W is placed approximately in the center of the vacuum chamber 2, as shown in Figure 7, the plasma P spreads from the edges (W1 and W2) of the substrate W to the outside of the substrate W. As the plasma P spreads, even if the density of sputtered particles on the surface of the substrate W (indicated by the thick arrow in the figure) is approximately the same, the plasma P spreads outward from the edges (W1 and W2) of the substrate W, making the density of sputtered particles slightly lower than at the center of the substrate W. As a result, the thickness of the film deposited decreases as the distance from the edges (W1 and W2) of the substrate W increases. This causes variations in the thickness of the film deposited on the substrate W.

[0029] Furthermore, when extension plates 20a and 20b are arranged so as to contact the respective ends (W1 and W2) of the substrate W, even if sputtering is performed while the substrate W is moved within the vacuum chamber 2 by the reciprocating scanning mechanism 15, as shown in Fig. 8, there is no decrease in film thickness from the center of the substrate W toward the ends (W1 and W2), just as in the case where the substrate W is stationary as shown in Fig. 6. In other words, even if the plasma P spreads as the substrate W moves and the density of sputtered particles decreases, this effect is received by extension plate 20a arranged so as to contact end W1 of the substrate W, and not by the end W1 side of the substrate W.

[0030] On the other hand, if the extension plates 20a and 20b are not provided at the ends (W1 and W2) of the substrate W, and sputtering is performed while the substrate W is moved within the vacuum chamber 2 by the reciprocating scanning mechanism 15, as shown in Fig. 9, the film thickness decreases from the center of the substrate W toward the ends (W1 and W2). In other words, as the substrate W moves, the plasma P spreads and the density of the sputtered particles decreases, and this effect is felt on the end W1 side of the substrate W, so the film thickness of the film formed on the end W1 side of the substrate W decreases.

[0031] Moreover, the surfaces of the extension plates 20a and 20b disposed at the ends (W1 and W2) of the substrate W are flush with the surface of the substrate W on the film-forming side, so that the boundary between the substrate W and the extension plates 20a and 20b is also flush. This makes it possible to eliminate volume fluctuations in the discharge space at the ends W1 and W2 of the substrate W, which are included in this boundary, and thus eliminates variations in the thickness of the film formed on the substrate W, further improving the uniformity of the film formation.

[0032] In this way, to eliminate variations in the thickness of the film formed and improve the uniformity of the film, it is preferable to arrange the extension plates 20a and 20b as close as possible to each of the ends (W1 and W2) of the substrate W. For this reason, as described above, it is most preferable to arrange the extension plates 20a and 20b so that they are in contact with each of the ends (W1 and W2) of the substrate W. However, the extension plates 20a and 20b may also be arranged close to each of the ends (W1 and W2) of the substrate W without contacting each other. In this way, when the extension plates 20a and 20b are arranged close to the ends W1 and W2 of the substrate W, the extension plates should be arranged at a distance from the ends of the substrate W that prevents variations in the thickness of the film formed at the ends W1 and W2 of the substrate W.

[0033] (Relationship between film distribution and extension plate) The graph in FIG. 10 shows the difference in film thickness distribution during film formation depending on whether or not extension plates 20a and 20b are provided, which are arranged to contact the edges W1 and W2 of the substrate W. The graph in FIG. 10 plots the distance (arrangement position (mm)) from the center of the substrate to be film-formed (0)) to the edge of the substrate, and the vertical axis plots the film thickness measured at each arrangement position. The conditions for obtaining this graph were as follows: in the sputtering apparatus 100, the power supplied to the antenna 5 was 20 kW, the bias voltage applied to the target T was 400 V, the pressure in the vacuum chamber 2 was 0.5 Pa, and the ratio of O2 to the inert gas in the vacuum chamber 2 was 2.5%. The graph in FIG. 10 shows the film thickness distribution with and without extension plates 20a and 20b.

[0034] 10, when the extension plates 20a and 20b are provided on the substrate W (with extension plates), there is less variation in the film thickness distribution than when the extension plates 20a and 20b are not provided on the substrate W (without extension plates). In other words, it can be seen that when the extension plates 20a and 20b are provided on the substrate W, the film formation uniformity is superior.

[0035] The graph in FIG. 11 shows the difference in film thickness distribution during film formation due to differences in the width of the extension plate. In the graph in FIG. 11, similar to the graph in FIG. 10, the horizontal axis represents the distance (arrangement position (mm)) from the center of the substrate to be film-formed to the edge, with 0 representing the center. The vertical axis represents the measured film thickness at each arrangement position. The conditions for obtaining this graph were as follows: in the sputtering apparatus 100, the power supplied to the antenna 5 was 20 kW, the bias voltage applied to the target T was 400 V, the pressure in the vacuum chamber 2 was 0.5 Pa, and the ratio of O2 to the inert gas in the vacuum chamber 2 was 2.5%. The graph in FIG. 11 shows the film formation distribution when the width of the extension plates 20a and 20b (the length in the direction away from the edges W1 and W2 of the substrate W) was 250 mm and 300 mm.

[0036] 11, the wider the extension plates 20a and 20b are, the less variation there is in the film thickness distribution. In other words, the wider the extension plates 20a and 20b are, the more uniform the film formation is.

[0037] In order to prevent a decrease in film thickness at the edges W1 and W2 of the substrate W, it is preferable that the extension plates 20a and 20b are wide, but it is sufficient if the width is approximately the same as the spread of the sputtered particles. That is, as shown in Figure 4, when the pitch width of the multiple targets T is Y and the width of the extension plates 20a and 20b is Z, it is preferable that the following relational expression (1) is established.

[0038] Y≦Z≦2Y (1) For example, if the pitch width Y of the targets T is 200 mm, the width Z of the extension plates 20a and 20b is about 250 to 400 mm.

[0039] The upper limit of the width of the extension plates 20a and 20b is set in consideration of the size of the sputtering apparatus 100, and the lower limit is set so as not to cause a decrease in film thickness at the edges W1 and W2 of the substrate W. In this way, the width of the extension plates 20a and 20b can be set based on the pitch width of the targets T and the size of the sputtering apparatus 100.

[0040] In addition, in this embodiment, the plate-shaped extension plates 20a and 20b are described as extension members disposed at the edge of the substrate to extend the surface of the substrate on the film-forming side, but the present invention is not limited to this. For example, the extension members may have any shape as long as they have at least one surface that extends the surface of the substrate on the film-forming side.

[0041] Furthermore, although the example has been described in which the surfaces of the extension plates 20a and 20b arranged to contact the respective ends (W1 and W2) of the substrate W are flush with the surface of the substrate W on the film formation side, the present invention is not limited to this. For example, the extension plates 20a and 20b may be arranged behind the substrate W, i.e., in a direction away from the target T. Furthermore, the extension plates 20a and 20b may be arranged so as to be inclined obliquely upward (toward the target T) from the respective ends W1 and W2 of the substrate W.

[0042] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0043] 2 Vacuum container 2a side wall 3 Board holding part 4 Target holder 5 Antennas 6 High frequency power supply 9 Insulation 10 Target bias power supply 12 Insulation cover 15 Reciprocating scanning mechanism (scanning mechanism) 20a, 20b Extension plate (extension member) 100 Sputtering equipment IR high frequency current P plasma SR Scanning Range T Target W substrate W1, W2 ends X array direction Y pitch width Z extension plate width

Claims

1. A sputtering apparatus that sputters a target using plasma to form a film on a substrate, a vacuum vessel that is evacuated and into which a gas is introduced; a substrate holder that holds the substrate in the vacuum chamber; a plurality of target holders that hold the targets facing the substrates in the vacuum chamber; a plurality of antennas arranged in parallel at a distance from a film-forming side surface of the substrate held by the substrate holding unit, and arranged alternately with the targets held by the target holding unit; an expansion member that expands the film-forming side surface of the substrate, the extension member is disposed on the substrate holding portion so as to be in contact with or in proximity to an edge of the substrate when the substrate is held by the substrate holding portion; a surface of the extension member disposed on the substrate holding part is flush with a film-forming side surface of the substrate held by the substrate holding part, the plurality of target holders are arranged at equal intervals, When the pitch width of the target is Y and the width of the extension member is Z, the following relational expression (1) holds: Y≦Z≦2Y (1) Sputtering equipment.

2. 2. The sputtering apparatus according to claim 1, wherein the extension member is disposed on the substrate holding portion so as to contact or be in proximity to all edges of the substrate held by the substrate holding portion.

3. 3. The sputtering apparatus according to claim 1, further comprising a reciprocating scanning mechanism for reciprocally scanning said substrate holder.

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